1. Field of the Invention
This invention relates to polyamide resin composition having distinguished impact resistance, moldability and manufacturing stability and their manufacturing method.
2. Description of the Prior Art
Recently, for the purpose of improving the impact resistance of polyamides, resin compositions having various polyolefins incorporated have been investigated. In order for the impact resistance to be improved, it is required that the polyamide and polyolefin present a tightly combined state, and for such purpose, technologies of modifying polyolefin have been proposed. As a typical example of the polyamide and modified polyolefin compositions and their manufacturing methods heretofore known, a method of preparing a modified polyolefin having carboxyl or acid anhydride groups and melt compounding it with a polyamide as described in U.S. Pat. No. 4,174,358 or a method of preparing a modified polyolefin having imide or amide groups and melt compounding it with a polyamide as described in U.S. Pat. No. 4,612,346, may be cited.
However, it was known that the resin compositions shown in U.S. Pat. No. 4,174,358 had difficulties in flow at the time of injection molding and in the surface appearance of the molded articles. The resin compositions shown in U.S. Pat. No. 4,612,346 were found to have a problem that they were of poor stability in manufacturing, that is, the gut emitted from the extruder was of poor spinnability, resulting in frequent cutting of the gut. Also, in these prior disclosures, a method of preparing a modified polyolefin having various functional groups and melt compounding it with a polyamide is disclosed, and it is noted as one of the requisites that as the polyamide and modified polyolefin have to be finely admixed with each other, the modified polyolefin should not be cross-linked substantially.